In a mobile communication system using code division multiple access (CDMA), 1×EV-DO (1× evolution-data only) achieving high speed data communications is provided (Japanese Patent Application Publication No. 2002-300644 (pages 2-3 and FIG. 1), for example).
In 1×EV-DO, a single carrier is assigned to a single user (radio communication terminal). Furthermore, the implementation of a so-called “multicarrier” (n×EV-DO) has been in consideration, the multicarrier achieving even higher speed data communications by assigning multiple carriers (three carriers, for example) to a single user.
In addition, in 1×EV-DO Rev. A, priority control (QoS control) can be performed for each of data flows of voice data (VoIP), file transfer or the like in order to appropriately handle the data flows.
Moreover, in a case of the multicarrier, a data flow transmitted using a logical channel is subjected to serial-parallel conversion (S/P conversion) in a physical layer, and is assigned to multiple carriers.